The method of electrochemical impedance spectroscopy (EIS) can be applied to study structural characteristics of sand which consists of sand particle and pore solution. The EIS diagrams of Bode and Nyquist, equivalent circuit of the whole sand system with different particle size and water content are studied and analyzed by using CS350 electrochemical workstation. The results show that the EIS of sand presents pre-Randles model and its equivalent circuit components include pore solution resistance, solid-liquid interface capacitance, charge transfer resistance anddiffusion impedance. The modulus of impedance in Bode diagram decreases with the increase of testing frequency, particle size and water content of sand. When water content is kept con- stant, the pore solution resistance tends to keep constant while solid-liquid interface capacitance increases, the charge transfer resistance and Warburg diffusion coefficients decrease with the increase of particle size. When the particle size is kept constant, pore solution resistance increases while solid-liquid interface capacitance and Warburg diffusion coefficients decrease with the increase of water content. The concluding research results are expected to broaden applications of EIS methods in geotechnical engineering.